Machine for grinding drills and similar tools



Oct 1 '1 4 D.T. E. FIELDING 2,408,618

MA QHINE FOR GRINDING DRILLS AND SIMILAR TOOLS Filed A rii 15," 1945 3 Sheets-Sheet 1 4 P .QW M

ATI'ORNEYS Oct. 1, 1946. D. T. E. FlELDlNG MACHINE FOR GRINDING DRILLS AND SIMILA R TOOLS Filed April 15, 1945 3 SheetsSheet- 2 .IIIL

R E m/ LIN VEQ 0 WWW n Oct. 1, 1946.f D. T. \EQFIELDING 2,408,618

MACHINE FOR GRINDI'N G D RILLS AND SIMILAR TOOLS Filed A i-i1 15, 1945 J3SheetS-Sheet s A F1 '.9. ,FiglO. L mvEN oR.

ATTORNEYS Patented Oct. 1, 1946 UNITED STATES PATENT OFFICE David Thomas Edward Fielding, Middleton Junction, England V a Application' April 13, 1945, Serial No. 588,158 v i In Great Britain May 15, 1944 a This invention relates to improvements in machines for grinding twist drills and similar tools of the kind in which the tool is passed across the face of the grinding wheel. I r

According to the invention the grinding wheel 1 Claim. (01. ale-1219i 1 means for securing the tool in its supporting is mounted on a horizontal shaft so that its 1 A grinding face is vertical and the tool is supported at a suitable angle to the grinding face by a bracket mounted on a pivot carried by a second bracket so that it can be movedflto bring the tool into various positions relative to the grinding face when grinding clearances on the cutting edge such as the cutting edge clearance and additional clearance behind the cutting edge clearance and for thinning the drill .point,.the second bracket being pivoted on a third bracket so that it can pivot in a vertical plane to move the tool in an arc acrossv the grinding face and the third bracket being mounted on th frame of the machine so that it can be moved verti-.-

cally to adjust the height of the tool supporting 1 bracket to suit various sizes. of tools and bring the axis of the tool to be ground into the correct position in relation to the arc. along which the tool is moved over the grinding face of th grinding wheel. r g

The tool is preferably supported'by adjustable carriers formed with a V or other shap d groove slidably mounted on the tool supporting bracket.

The invention is illustrated in and will be described with reference to the accompanying drawings in which: 1

- Fig. 1 is a side elevation partly in section of a grinding machine constructed in accordance with the invention. I

Fig. 2 is a plan ofsame with thedriving motor removed.

. Fig. 3 is a section on line 3-3 Fig. 1.,

Fig. 4 is a section; on line 44 Fig. 1.

Fig. 4 shows diagrammatically a modified construction of tool carrier particularly for tools of small diameter. g

Fig. 6'is a section on line 6-6 Fig. 5.

Fig. 7, 7 7 and 7 are viewsof the tool carrier illustrated in Fig. 5 and 6 showing means for setting and centering the tool in the carrier.

Fig. 8 is a section taken on the line 88 in Fig, l, and

Figs. 9 and 10 are sections taken on said section line, illustrating th different angular positions of the tool when grinding the cutting edges thereof.

Figs. 11 and 12 are a plan and transverse section respectively and drawn to a larger cale, of

carriers. I V

In. the form of the invention illustrated in the drawings the grinding wheel A is driven directly from the electric motor B being secured on the endof the shaft b thereof. The motor B is-afiixed to a slide C mounted in horizontal guides c on the frame D. The slide C and with it the motorB and grinding wheel A, is moved towards the tool A by a cam or eccentric c actuated by a handle 0" against the pressure of a return spring 0 the movement of the cam 0 beyond its maximum throw being prevented by the stop 0 The cam c acts on the head of a screw 0 in the end of the slide Cand affixed therein by the set screw c". The forward position of the grinding wheel A can be varied by varying the distance which the head of the screw 0 projects from the rear of the slide C thus allowing the wheel A to be adjusted asits grinding face a becomes worn.

The tool supporting bracket E is mounted on a vertical pivot .f carried by a second bracket F. so that it canbe moved in a vertical plane to vary the angle of the cutting edge of the tool A relative to the wheel A for thepurpose of forming the cutting edge clearance, the additional clearance behind the cutting edge clearance and for thinning the point of the tool i.e. for making as narrow as possible the part between the two cutting edges. Figs. 8, 9 and 10 show these three positions of the bracket E relative to the bracket F. The bracket E is formed on its edge with three notches e eB-ande adapted to be engaged by a screwed or spring loaded stop ,1 carried by the bracket F. When the bracket E is in the 7 position shown in Fig. 8 with the notch e enfor grinding the cutting edge with the cutting edge clearance; when it is in the position shown in Fig. 9 with the notch e engaged by the'stop f it is in the position for grinding the extra clearance behind the cutting edge clearance of the tool A and when it is in the position shown in Fig. 10 with the notch e engaged by the stop I it: isiin the position for thinning the point'of the tool A. By varying the various stop positions the cutting edges of the tool can be ground to any desired angle and if necessary where a relatively large clearance to the cutting edge is desired, this may be obtained by moving the bracket E so that the notch e is beyond the stop 1*.

. The tool A is carried on the bracket E by supports E and E the bearing surface of each being in the form of a y groove. T e Support 3 E adjacent to the wheel A is fixed and the support E is slidably mounted on the bracket E being secured in any desired position by the clamp 6 The tool is held against the wheel A by a screw e which is also slidably mounted on the bracket E and adapted to be secured in1 any desired position relative to the wheel A by the clamp 6 For small tools, the supports E and E may be replaced by an expandible chuck or holder 9 on the end of a spindle 9 carried in a housing. G'

slidabfy mounted on the bracket E as shown in Figs.5 and 6 a i To facilitate the correct centering of the tool in the holder 9, which is difficult with very srnall drills, the housing G may be removed from the bracket E and placed on a centering device K such as shown in Figs '7, 7 7 and 7. The device K comprises two plates k and 70 having their operating faces k and lr situated in the same plane so that when the end of the tool A is placed in the device the points of the tool will be correctly set as indicated in Figs. T and 7.

The bracket F is mounted on a horizontal pivot it carried by a bracket H. The bracket F can be oscillated in a vertical plane to traverse the cutting edge a of the tool A in an are over the face of the grinding wheel A.

The bracket H is mounted in vertical guides at carried by the frame D for adjusting the-height of the tool A relative to the wheel A for the correct setting of the tool according to its diameter. The height of the bracket His controlled by the cam 72 on the sleeve h which is operated by the hand wheel h The wheel h is preferably provided with a graduated scale It (see Fig. 3) working over a fixed. indicator It so that the correct setting of the bracket H for-any given diameter cam h and located in the horizontal position shown in Fig. 9. The face of the wheel A is then moved up to the first cutting edge of the tool by the cam or eccentric c and any final fine adjustment made by the screw 6 carried by the member E The motor B is then started and the bracket F oscillated about its pivot h to cause the cutting edge of the tool to travel in an are over the face of the wheel A until suiiicient material has been ground off.

' 1 .The wheel A is then moved backwards from the tool by the cam motion C, the tool reversed in the supports E and E and the wheel again 7 brought into its operative position to grind the second edge so that both edges are ground for Fig. 10 for thinning the point at both sides. When of tool A within the limits depending on the ing the cutting edge clearance and the extra clearance behind the cutting edge clearance.

When grinding a large drill it may be desirable to secure the drill in the carrier E and means for so doing are illustrated in Figs. '11

and 12. Themeans illustrated comprise a peg e at the bottom of the V groove in the carrier E which engages one radial face of the. drill and/ or a clamp 6 adjustable mounted ona rod e carried by an extension of the carrier E and adapted to' be secured against the circumferential face of the drill.

In operation the tool A is placed on the supports E and E and the bracket E raised to the correct height for the diameter of the tool by the l in this position no oscillating movement is given to the bracket F.

As the tool A passes in an arc across the face of the grinding wheel A it tends to keep the face true and prevents the formation of rooves therein.

I claim:

In a machine for grinding twist drills and similar tools of the kind referred to, the combination of a grinding wheel mounted on a horizontal shaft so that its grinding face is vertical and a frame carrying the said shaft, a bracket supporting the tool at a'suitable angle to the grinding-face of the wheel; a second bracket on which the tool supporting bracket is pivotally mounted so that the latter can be moved to bring the tool into various positions relative to the grinding face when grinding clearances on the cuttingedge such as the cutting edge clearance and additional clearance behind the cutting edge clearance and for thinning the drill point, a third bracket on which the'second bracket is mounted to pivot in a vertical plane to move the tool in an arc across the grinding face of the wheel and guides carried by the frame on which the third bracket is mounted so that it can be moved vertically to adjust the height of the tool supporting bracket to suit Various sizes of tools and bring the axis of the tool to be ground into the correct position in relation to the are along which the tool is moved over the grinding face of the grinding wheel, a slide or the frame on which the grinding wheel is mounted so that its grinding face can be moved to and away from the tool, a spring tending to move the wheel in a backward direction and a cam for moving itina forward direction against the pressure of the spring.

DAVID THOMAS EDWARD FIELDING. 

